Geological Society. 261 



Of the head, the only portion yet recognized is the part of the brain- 

 case behiad the parieto-frontal suture. It indicates a skull as 

 large as that of the red-throated Diver, which it resembles in de- 

 tails of structure. The vertebral column is represented by lower 

 cervical vertebrae, which have the centrum small and compressed 

 from side to side. The dorsal vertebrae are also small, are rounded 

 on the underside as in the Gannet, and often have the articular 

 ends biconcave, or have a concavity in the centre of the saddle. 

 There were transverse processes as in modern birds ; and the riba 

 had a similar double articulation. The sacrum was unusually large, 

 and included many vertebrae. Its anterior end resembles that of a 

 Gull's sacrum, in being flattened or concave. The vertebrae are 

 rounded anteriorly, and distinguishable from each other; but poste- 

 riorly thej' are blended, and resemble the postarticular part of the 

 sacrum of the Diver. Some small vertebrae were thought to be 

 caudal, and considered to be probably elements of the ploughshare. 



No trace of any bone of the anterior limb has been detected ; 

 while of the hinder limb, the femur, tibia, fibula, and tarso-meta- 

 tarsus are all known. The femur and tarso-metatarsus are the 

 bones most like those of the Diver. The fibula is unusually large. 

 The tibia has a moderate patelloid process, and shows resemblances 

 to several water birds. The bones are so fragmentary that the size 

 of the animal can only be given roughly as similar to that of the 

 Diver, but with a shorter neck. The affinities of the animal are 

 strongest with Colymhus. It also closely resembles Prof. Marsh's 

 Cretaceous genus HeKperornis, and, like that genus, may be supposed 

 to have had teeth. The species were described as Enaliornls Barretti 

 and E. Sedgivicli. Some bones were also described thought to 

 indicate birds in which the extremities of the bones remained un- 

 ossificd throughout life. 



" On two Chimaeroid Jaws from the Lower Greensand of New 

 Zealand." By E. T. Newton, Esq., F.G.S., of H. M. Geological 

 Survey. 



The two jaws which were the subject of this communication form 

 part of the collection of fossils from the Lower Greensand of New 

 Zealand deposited in the British Museum by Dr. Hector. One of 

 the specimens, a right mandible, was referred by the author to 

 Ischyodus hrevirostris, Ag., a species from the Gault of Folkestone, 

 hitherto known only by name, no description or figure of it having 

 been as yet published. Through the kindness of the Earl of Ennis- 

 killen, the original type specimen of this species was exhibited to 

 the Society. The author theu described a perfect mandible from 

 the Cambridge phosphatic deposits, and stated that the examina- 

 tion of a large series of specimens showed a considerable variation 

 in the form of the teeth in different individuals. The New-Zealand 

 mandible was then compared with these British sjjecimens, and was 

 said to differ less from some of them than they did among them- 

 selves. 



The second specimen, a small right maxilla, possessing but one 



